Question

In a conductor, electrons are flowing from $B$ to $A$. What is the direction of conventional current? Give justification for your answer. A steady current of $1ampere$ flows through a conductor. Calculate the number of electrons that flows through any section of the conductor in 1 second.

Answer 1

Step 1: Given data

Current flowing through the conductor is: $I=1A$

Required time for electrons flow: $T=1s$

Step 2: Formula Used

1. Charge is the product of current and time, i.e, $Q=IT$.
2. Also, charge is given as $Q=ne$, where $n$ is the number of electrons and $e=1.602\times {10}^{-19}C$ is the charge of an electron.

Step 3: Find direction of current

1. In a current-carrying conductor, the flow of electrons is the flow of negative charges and the direction of current is in the opposite direction of electrons flow.
2. So the direction of flow of positive charge is taken as the direction of conventional current.
3. Thus, when electrons are flowing from $B$ to $A$ in the conductor, the direction of current will be along with from $A$ to $B$.

Step 4: Find the number of electrons

Calculate the charge using the formula

$\begin{array}{rcl}Q& =& IT\\ & =& 1A\times 1s\\ & =& 1C\end{array}$

Calculate the number of electrons using the formula

$$\begin{gathered} q=ne \\ \Rightarrow n=\frac{q}{e} \\ \Rightarrow n=\frac{1C}{1.602\times {10}^{-19}C} \\ \Rightarrow n=6.25\times {10}^{18} \end{gathered}$$

Therefore, the direction of the current is along $A$ to $B$. And the number of electrons that flow through the conductor in $1second$ is $6.25\times {10}^{18}$.